Multiple sclerosis (MS) is a disease that steadily erodes the ability for nerve cells to communicate and this leads to all kinds of neurological symptoms, often slowly progressing to severe cognitive and physical disability.

But one of the most common symptoms is depression. It’s often attributed to the mental toll of managing the disease which has no cure.

But recent research published in the journal Biological Psychiatry describes a physical connection between MS and mood.

Using magnetic resonance imaging (MRI) scientists found that the hippocampus, the brain area responsible for long-term memory, is smaller in people suffering from MS than in healthy adults.

They found a connection between this atrophy in the hippocampus and a hyperactivitiy in the hypothalamic-pituitary-adrenal axis (or HPA axis) in MS sufferers. The HPA axis is part of the neuroendocrine system that manages stress.

The authors note that this link between hyperactivity in the HPA and an atrophied hippocampus is consistently seen in those with chronic depression, yet this correlation has never been studied in MS patients.

The next step, of course, is to compare depressed populations—those with MS and those without—to look for any significant differences in how depression progresses in each case.